Cross drive for heavy vehicles



0c:w 13, 1953 o. K. KELLEY 2,655,054

CROSS DRIVE FOR HEAVY VEHICLES (Ittornegs Oct. 13, 1953 o. K. KELLEY cRoss DRIVE FOR HEAVY VEHICLES lO Sheets-Sheet 2 if 97 /f Original Filed July 21, 1947 Oct. 1 3, 1953 Q K KELLEY 2,655,054

CROSS DRIVE FOR HEAVY VEHICLES Original FiledvJuly 21, 1947 10 Sheets-Sheet 5 Oct. 13, 1953 2,655,054

O. K. KELLEY CROSS DRIVE FOR HEAVY VEHICLES Original Filed July 21, 1947 10 Sheets-Sheet 4 rif I lnventor Gttorneg Oct. 13, 1953 KELLEY CROSS DRIVE FOR HEAVY VEHICLES Original Filed July 21, 1947 @Ln/fk K. KELLEY O. K. KELLEY CROSS DRIVE FOR HEAVY VEHICLES 10 Sheets-Sheet 6 @riginaly Filed July 21, 1947 Oct. 13, 1953 o. K. KELLEY cRoss DRIVE EOE HEAVY VEHICLES Original Filed July 2l, 1947 l0 Sheets-Sheet '7 :Smmmor 0mm: K. KELLEV /WMW, Mam, M E 5MM Cittormjs Oct. I3, 1953 o. K. KELLEY 2,655,054

CROSS DRIVE FOR HEAVY VEHICLES Original Filed July 2l, 1947 10 Sheets-Sheet 8 LEFT FIGHT Octo 13g O'VK. CROSS DRIVE FOR HEAVY VEHICLES Original Filed July 21, 194'? l0 Sheets-Sheet 9 w IIVVI, will.

UNL/m Af. KELLEY Lttornegs Oct. 13, O. K. KELLEY CROSS DRIVE FOR HEAVY VEHICLES Original Filed July 21, 1947 10 Sheets-Sheet l0 [lll/110111111 'lll Ihwentor' (ttornegs Patented Oct. 13, 1953 CROSS DRIVE FOR HEAVY VEHICLES Oliver K. Kelley, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application July 21, 1947, Serial No.

762,414. Divided and this application November 4, 1948, Serial No. 58,197

This is a divisional of my application, S. N. 762,414, entitled Cross Drive for Heavy Vehicles led July 21, 1947, now Patent U. S. 2,596,931.

The present invention relates to drive mechanism for large heavy vehicles such as military tanks, tractors and the like, having track laying mechanism steered by variable speed ratio differential means.

it relates more particularly to such mechanisms in which quick steering and reversing of direction of travel is required, and for which the drive mechanism embodies an arrangement of units producing plural and continuously variable torque components combined advantageously for the stated purposes.

A primary object is to provide a common drive to right and left hand track drivers which includes final drive output gear units commonly driven thru divided torque paths, one of which is supplied by coupled differential gearing driven from a prime mover and the other of which is driven by combined selective change speed gearing and fluid torque converter mechanism, for the purpose of obtaining maximum smoothness of torque during speed ratio transition periods and for obtaining similar smoothness in steering effect created by establishing of a variable range of selected reaction torques in said differential gearing.

The present invention representing improvements over the applicants Letter Patent applica'- tion No. 588,475, filed April 16, 1945, now Patent U. S. 2,585,790, in certain important particulars, it is obvious that the general objects stated in that application are likewise sought herewith insofar as the subject matter of both applications would permit. v

A. further object is to provide a, power transmission system for track laying vehicles having concentric primary and nal drive mechanisms with parallel shaft differential mechanism coupling to the said nal drive mechanisms so as to provide divided and recombined torque for the purposes above stated, of the same hand of rtation of said mechanisms, for forward drive, the advantages including improved power output with less wear due to lower friction losses.

An important object is the provision of a high degree of compactness of the driving and steering assembly obtained by nesting of the variable speed drive the differential unit and the output unit parts, resulting in extremely low torsional couples in the supporting structures with balancing out of the reaction couples ordinarily experienced in devices of this character,

11 Claims. (Cl. 'I4-710.5)

2 In the demonstration herewith another important object is achieved, that of providing exceptionally useful efficiency in the variation of the split-torque ratio favoring the transfer of torque to the uid torque converter portion of the drive with increased converter eiciency,

resulting in an extension of useful torque converter speed range having as a further resultant a rising engine speed characteristic in this procl ess.

An additional object is to provide a dynamic steering-driving assembly having continuously variable speed ratio drive compounded from divided torque paths one of which includes a fluid torque converter adapted to deliver a variciency of the fluid torque converter.

A further object is the provision, in such an assembly as stated above, of means for varying the Vehicle steering radius to increase and decrease with vehicle speed for sharp steering at low speed and stabilized steering at high speed, and of means for pivoting the vehicle at standstill by the same means utilized for said variable radius steering.

It is an important object herein to provide a i driving and steering assembly which shall utilize the power dividing and recombining feature outlined above and which shall apply the variable steering torque component delivered to the final drive output units thru a mechanical gear train or trains while applying the continuously variable torque converter and connecting reduction gear trains, the ratios of which are selective for plural forward, and reverse drives.

It is an added object to provide herein a dynamic power steered and driven assembly for vehicles in which under given selected drive conditions, may embody means for reapplying a torque from the output to the input side of a unit of the variable speed drive train, for obtaining a higher net torque at a reduction speed ratio than the said train would normally deliver. Further and additional objects will appear in the discussion of the following specication.

Fig. l is a transverse sectional view of the driving assembly, showing the input shaft from the engine geared to the primary power drive, and the output sprocket drivers at the right and left.

Fig. 2 is a detailed section View of the differential coupling arrangementloflFig. 1 for the powered vsteering* ee'ct; derivedthru thepom.- pensator'grou'p at the -`top of Fig. l'. Fig. 3 is a part section taken at 3 3 of Fig. 2 to show the relationships of the differential gear elements.

Fig. 4 is a section taken at .4i-.44:01:1Fig. 1..to show the operating mechanism for the rreajgion brake 45 for low gear drive.v g.V ifnwis, a similar part section taken at 5-5 of Fig. 1 to -show the somewhat different arrangement for the actuation of brake 46 which controls thespedfof the Fig. 1. It should be noted that brake 5| is controlled in accordance with Fig. 4, and brakeg in the manner of Fig. 5. Fig. 6 is a sectional detail of the external mechanismponnected l.tothe construction of' Fig'.5.V W

Fig. 7' shows' an alternative .construction `to that of Fig. 2 being .a s: tional viewer va .bevelgear l.differential di y. inctnflrom the spre/gear differential of Fig.1 2. Figffvlalso shows acornpensator group 'clutch' arrangement alternative to that shown in Figs. 1v arid-'2, Iand .shoy'vs elec- 4trical steering brake meansfin Vplace ofthe fluid pressure system shown in Fig. '1.x4

Fig. 8 is an enlarged viewof the sectional structure at the right.' of -lfmodied by the substitution of a disc brakefor the output sprocket shaftsof-Fig.1.""""` F'igsfQV and 1Q show 4elevation sections right angle planes respectiyjely..forn .the mechanical connections. to .the vcontrol valvaslfor .the steering action applied by iiuidpres's'uretofthediiierential steeringl clutches o'fFig 1.'`|` Y Figs. 11 and 12 .represent V.the drivfselection valVe and its external' controljzrespetivelyfor the modiiieation System onownin Fie-v f11 in diaerainniatie .fonn- The .twoioioerinnlraiveo ,of Figs-fg and .10 are Shown.intnenonenrient oornel' 0f Fig- 114.."1111 .theiait leion. VVEQ Fia 11 is Shown. adiaoent ca ;.tnelfn toward the. center of therdiagram. Fig` 13 is alsectional detail of a vacuum-neononoivewaive. adaiotedto euohion the ratio downrehiftieieot -Dyooonttolline the aoolioation of iinenreoonre ,admitted .to the transmission drive 4 systernf .byi the shifter Vvalve of Fia 1'1- -The diagrarn-oieia :.14` snows .the valve of Fig. 13 atftheriel1totthe ahifter A:valve- Fig. 14 is a schematic diagram aof a-;{ i1 1icl pries- Sure System .for control 4and onerationoffthe .drive structures Fig. 1. Fig. -15 i s adetailed sectional view of the pressure ,regulator Ivalve-,of Fig. 14. .Fig 16,15 a sectional ,detailed Aviewiof auxiliary .valving energised during the power steering interval as controlled. bythe Fig. .14 arrangement. Y v

Fig. 17 is a schematic diagram of a combined fluid pressure and electrical control system, as a modication of the Fig. 14 system, wherein the ratiolcntrolling' vali/ing isfby iridividulal valvesl eieotno'ali'y operated! ,and otne' .oinoiontiationo are fniorifiai;y 'aofnitnerexnianeo in. sietaiif. 18 ia a View. Similar to that .o f Eiel, oi the Pres? sure regulatorvalve ofv ll'jwF'ig.` 19 is a detailed sectional view v o ffone of the solenoid: actuated control val'yCSSlrqwn-inliigflf?, herein the control impulses such as supplfedfrom an operators control lsyster'n.v '.20 diagrammaticallyare c d.` to fluid` prese owespggls.

'f1-f5 output shaft on the right -of` theassembly A10-atingin-thef-safme general manner except that the rariaple speedfratio input is applied to the i ndthe power steering differential @vingtaine iinfgears.

ln bothLthesplitutorque principle is used, of

the input torque thru two trains, varied .dr1ve and power steering, and combining the torques in the output gear units.

.JI-Thisdividing and combining principle is shown in a somewhat different form in my Letters Patentusiasta-138 iosoedootooer .,1'1. .1.93am ,the dri-ve for the .So-tailed Hiforarnatie transmission. andfinmyrnettere Patenti?, 512.211.233 issued August 13, 1940.

,.Inpthe present lantancorrierit. the d iferential power -ftrain consists .of Shafts .36 .and 55 geared at. .4.1. and, 42. .35 to output-Son ,gears 24 and 38, the-.shafts being normally coupled by olutoh C for unitary rotation in the same vhand o f rota.- tion. this feature beine diierent from the arrangement in Serial 130,588,475, where the secondary power group has `v two ,shafts geared 4for opposite rotation.

For economy .of space `and. vfor resolution Vof drag couples toene, `o0.111?entri@ alignment. the power steering differential centerline is herein concentric with the output unit centerlinevIt has been found that theintroduction Vofthe splitrtorque principle into the compound fluid turbine andgear driveassemblies embodying dynamic steering provides a high attainable efciencyover comparative series unit drive assemblies Without impairing lthe :desirable drive characteristics .of the fluid units.

f I-nthepresent inventionthe power is delivered thruY a mechanicalpath and a hydraulic and mechanical path, the first including a planetary gear train having a planet lgear carrier rotating fixedlywith the output shaft, and having a sun gear and ring gear one of which couples to the output .of the fluid.- torque converter unit W. the .other -to the input side of the fluid unit.

Inthe -driye .pattern .of Fig. 1 the planet carriers 20, and are fixed to or integral lwith the output-sprocket shaftsr 2| and 31, and the sun gears 24 and 38 are `connected to the input side ofthe uid torque converter -W thru gears 25, 39, 4I, 42 and a differential gear assembly D which provides steering effect but has no resultant action directly `rupon the aforesaid-torque dividing operation.

YThe annulus gears I8 and 33 are cross-connectedrthru drum nanges of `central shaft 4D and are driven bythe output-member O ofv the fluid torque converter unit' W.

vFor neutral drive, this connection is interrupted as will be explained in detail further.

The construction shown in Fig.V 1 has engine shaft L furnishing input power, geared at 3, 4 F9 QQWEPE'PQ- Tn@ @W0 .Ou/51911@ 01" load menagere .and 31 .are eaononven .from adjacent final .drive Planetaryv Sear unita The Shaft 5 delivers Power. .to tneearrier members 6 of the oentraily located .oiiferential gear unit D, and simultaneously to the impeller l1 ofa fluid torque converter W, the output member O of which is fixed to hollow shaft 1.

.At the right of Fig. l shaft 1 is attached to sun gear 2 and at the left to sun gear l2, these sun gears acting as power input drivers for the combining and reduction ratio units. Nested lnside shafts 5 and l is shaft 45 attached to carrier 38 of the low gear unit, to annulus gear 33 of the adjacent final drive output unit, and at the left by a drum l'i to annulus gears i6 and i8 of the reversing and final drive units adjacent shaft 2|.

The combining output gear group 33, 31|, 33 at the right, drives carrier and output shaft 3l as a nal drive unit, while combining output group i8, i3, 24 at the left drives carrier 2|) and shaft 2| similarly.

The reduction gear group 2S, 2l, I2' provides low gear and coupled direct drive to shaft from shaft l, and the reverse gear group It, I3, I2 provides reverse gear drive to shaft et from shaft 7.

The gear groups I--iEi-Zl and 33-34-33 should be regarded as torque-combining variable ratio gears, and the shaft 48 with drums and 23 may be thought of as the cross-coupling input means for the torque-combining gears, while the combination 23-2l-l2 is the low reduction group and the combination |3-|3|2 is the reverse reduction group. The clutch i5-3| drives the coupling shaft 4|) at unit speed with shaft l, when energised.

The line of drive from the unit W therefore consists of final torque combining groups driven by change speed groups. Since the member 40 is the means for providing equal coupling to the annulus gears I3, 33 of each of the torque-com bining groups, it is called the coupling or crosscoupling member.

It is believed novel to divide the direct, forward and reverse groups in the manner shown. This feature yields advantages in distribution of weight, bearing loads, and in assembly arrangement for low differential speeds between adjacent rotating elements, as Well as in the coordinate distribution of the torques.

The output sprocket shafts 2| and 3'! are connected to and driven by the output unit carriers 25 and 35. The sun gears 24 and 38 of these units are driven from the power steering differential unit D, and the annulus gears I3 and 33 from the iiuid torque converter W and connected gear train.

In straight, non-steering drive, the secondary shafts 35, geared to drive the output unit sun gears are coupled for unit rotation by the friction clutch C, and the power steering differential annulus gears 33H53 rotate at the saine speed and in the same direction, causing the planet pinions 52 to stand still, and their carrier 6 to couple the turbine output member O to both annulus gears 33, 33 at unit Speed and rotation.

The engine-connected shaft l, bevel geared at fi drives the input shaft 5 which rotates the turbine impeller I and the power-steering differential carrier 3. This divides the engine torque thru the turbine W and the power steering differential train coupled to the sun gears 24, 38 of the output units.

rIhe intervening solid shaft 4f! cross-connecting the output units is attached thru drums and 23 to the annulus gears 33, i5 of both output units. With one component of torque applied thru the secondary shafts 35, 55 from the steering differential D to the sun gears 24, 38 of the output units, and another applied from the fluid 6.. turbine W and gearlng'to the annulus gears I3, 33 thereof, the carriers 20, 35 of the output units will revolve at a differential ratio of the components received, which will vary in accordance with the load and speed conditions, and the drive unit characteristics.

The drive is initiated by locking of low gear brake 45 to stop rotation of annulus gear 29. Assuming that the converter W may deliver a torque to sun gear I2' this torque is applied to carrier drum 28 of shaft 40, on the one hand, and is also applied thru shaft 'l to sun gear i2, the annulus gear I6 of drum |1 being driven. The component of this torque is applied to drums l1 and 28 of shaft 4D, and consequently to annulus gears I 8 and 33. Simultaneously shaft 5 is driving carrier 3, planet pinions 52 and annulus gears 43, 49 of the power steering differential D at input speed, and the teeth 48 and 43 of the annulus gears are rotating gears 43 and dil, drums 55 and 51, shafts 55, 33 and gears 4|, 42, the latter elements revolving in the same direction at the same speed.

Consequently output sun gears 2li and 38 deliver the same torque fraction to the output units, and the output carriers 20 and 35 receive equal combined torques.

For straight-ahead running, shafts 55 and 33 rotate together at the same speed, assuming the tractive efforts on sprocket wheels 23 and 31 are the same, since clutch C compels thorn to do so. While it may seem possible to omit clutch C, on the assumption that variation in right and left drive tractive effort could be compensated for by the differential action in unit D, it must be remembered that over uneven ground, if the arrival of one side at a point where traction is less permits differentiation, the passing of the same side to firmer ground could introduce a yawing tendency opposite in steering effect to that first experienced. The clutch C therefore couples the power steering train and its path of torque evenly to both output units, While the other path thru the torque converter W and its gearing trains is likewise evenly coupled.

At above a desired given speed, the clutch Sil-3| is locked, and the turbine output shaft 1 rotates the shaft 40 and annulus gears I8 and 33 at turbine output speed.

The recombining of divided torque in the output units is readily understood, as resulting from additive or subtractive components created in each unit by sun gear and annulus torque prom ducing a resultant summation torque on the output carriers 20 or 35 and shafts 2| or 31.

.For all practical purposes shaft 40 and drums ii and 28 serve as the rst train input members for the torque combining groups for each track driver.

The variable speed gear assembly of the first train consists of torque converter W receiving power from shaft 5 and gear li, and delivering same to the cross-coupling shaft 4|) acting as the output element of the separated forward and reverse reduction groups driven by shaft 5 thru sun gears I2 and I2.

The oneeway clutch F coupling shaft 5 to sun gear I2, acts to by-pass the torque converter W and couple shaft 'l to shaft 5 when there is vehicle motion or rotation of shaft l with no motion, or a lesser speed of shaft 5. This assures that shaft will not ever exceed the speed of shaft 5, and enables the operator of a vehicle to obtain a towed start of a stalled engine, for example. Y

AWhile'ait:.:vvcuillhbe .possibleeto placeuzlutch-zli;L sorasgto couple shaftillrftozshaft ,on the.' over-f. runtat :l-.tofl ratiopit'must' bememembered that shaft/40. is required-tabs.:drivenreverselyso that lockout means. forclutchzl would be needed. to permit this reverse rotationfofpll-to:5. 'I'heA positioning jshown .in the igures: herewith is simple V:and requiresfnoauxiliary y lockout since the :point of. torque conversion'for lreverse 1drivelies beyondthe-intermediatei coupling of vshafts 5 ands] bythe .clutchFn While it is. appreciated .that the prior art showsl one-,way clutches. arranged.- toby-pass -varf' iablespeed ratiordrivesto .couple output to input at 1-.tol ratio .gon .the .over-run; .thefproblem here-1 i in-solvedHis togutilize. thisfeffect-for ley-passing .a` torque AConverter combinationiwhich; may have 1 low overtakingftorque efliciencyfand doing so in the .intermediate :connectionto thestep ratio.` variable speed gearing Iofthe train, in order to retain;v steering ,stablity icon trol; on downhill runs..

The'overall driving trainherein shown provides a powerful low speed ratio reductionrange, and since such drives under .overtaking torque endeavor to speedup inputdriving elementsl to: extremely high overspeeds, the. drive system must be protected against the possibilityA of unrestrained run.away, aswell.

Assuming-the installation to be yina military tank andy running on adowngrade at considerable speed, if the fluid'of the torque converter W were :suddenly drained as-ma-y voccur inbattle from an enernyyshot, the momentumv of the vehiclewould vvno-longer beestrained bythe reverse -dragjoffthe :torqueconverterf W, and theV reverse stepfupqin: ratio= thru-.the -gear units vto shaft Ad could'not' beloaded .or restrained by engineV braking-,f Clutch F-thereforevacts`to couplek the converter-connectedfshafts .at 1 -to-1 before damaging high-:speeds underreverse torque are reached..

If vsuch amishapoccurs .when-fonev of the re- Y action 'brakes-.is..energisedV instead of iat atime speeds of vthe planet gears-of the Yassembly-could reach damaging velocities, andthe same would be true of 'a mishapto'the vcontrols for 4the low andreverse brake'bands '45er 5|-, respectively.

The brakes 50' and 45 fori-the respective output carriers 2!) and 35 of the torque-combining units enable the "operator to stop the -motion of either of shafts 2| or 3|, together'or selectively.V

Carrier 20 being stopped, for example, by brake 5S; the rotational componentlapplied to drum I'i .by shaft 40 is transferred thru planets i9 as aV reverse.componentA tosunrgear 24 and gear. '25,.the latter rotatingI gear4| shaft 55 in the same hand of rotation as drum This rotation is transferred to gear 44, which rotates crown gear 49 -and reacting thru gear, 52,` speeds up gear 45|".

Assuming normal: forward drive as indicated by the arrows in Fig. 1,.the. carrier 6 .of the difEeren-. tial unit D would rotate ,clockwise as viewed from the left, but gear 49 would be inopposite rotation; Clutch C- is disengaged-for this action.v

Sincethe -carrierfz has .forward clockwise motic-n andthe gear A45| has. reverse rotation thereto Vthe gear. ,49" revolves fwithla resultant motion atrincreased speedin-the .same l.hand of motion. as shaft 5. This:transmittedzthru gear 43, shaft 36 gear 42,:to sungearr .38. addsafdifferential com.- A. ponent 1to;.the v.coupling .of the combining unit.V 33-34-38 greater than was obtained thru .nor-

maloperationasocthat dah/ersprocket shaft 3 'Lmayff be rotated faster.

Thisact-ion causesrthe vehicleito A.pivot or,.steer about; a' point adjacent ithe. stopped@ shaft 2|,,

and causes themthenztready .to advance. faster.

In .reviewing` this peculiar. g relationshipY of .elemy ments, one should: consider-shaft 2| and carrier-,- 290i thefoutputunitat the-left of Fig. l stopped:Y

byabrake 50, while-thefcarrier'.acts as a reactor,

so that torque may be-transferred between. sun.

gearf24 'and annulusilSn If the gearunit at the right1is in lowgear, and the steering brakes are inactive,- shaft1 drives'lthe annulus gear 33 at. a' reduction-.consisting of the variableratioY of -theunit W-multiplied bythat of the right-hand gear unit, while the normal component. derived Y.

thru therotation oftthefunit Discapableof Ybeing` transferred to; shaft 3E,1gears42, 39 and sun.. gear 38.. However, since shaft 4is driving the other ,output .unit annulus |8 at. the same speedas annulus 33, the sun gear 24 instead of having a, fixed ratiov forward vcomponent derived from D, is now Vurged backward at .an Aoverspeed .-ratio.

by i, rotation ofannulus 8.'V

Assuming this. torque.` increment is. transfer.-

able to unit `D,. the diierental transfer gear 48.

would endeavor to rotate backward while the normal rotation of .-unit D would `be .urging the piece. 41,. 48, 49. to rotate forward.; The cluteh.Cbe-- ing lockedr engaged, no Y.differential'motion in. unit D could take place. If clutch C has suflicient braking. capacity, the reaction of the couple would then. have .the effect .of braking .drum

shaft .49.. ldruml and hence rotation of shaft 1,

sothat the net result. ofapplyingonly one outa put shaft brake vsuch as i5!! v.would be to brake the wholeforward; motion of the vehicle, withoutv steering effect.

Now if..clutch..C .be released, and brake 5D ybe applied,Y the,.backward.rotation of member 41,

48, 49would be .transmittedacross pinions of.

the differential unit D,` and member 41', 48', 49'., would .tend 4torotateforward faster than differential carrier -Sand shaft 5.' This speeds up the steering torque ldelivery shaft 35, gears 42, 39`

mechanism that the normal .slowing of member` 4T', 48,'49', for example, by steering brake 'B, also slows the rotation of gear 43, shaft 36, gears 42and 39V and sun gear 38, tending to cause the vehicle to steer .toward that side of the vehicle.

The vodd-.dual Aeffect obtained by applying one sidebrake, like .50,to stop one output element directly-while accelerating or speeding up the drive totheother sideoutput element, by merely opening across-connecting. clutch,.is believed entirely new. in. this. art.

The power. steeringpat'nlof torque begins with the shaft5driving carrier. 6 of the differential unit D. The gears.49,f4. are meshed with the planet gears 5?..and have external teeth..48, 48".

meshing with differential output gears 43,. 44..

The ,dividedshaft 36, turns the gears 4|,V 42 in xthe. .samehand ,.of. rotation, but of opposite hand to thev rotationofshaft. .5, and of gears 25,. driving the sun gears 24,` 38 of .the .output units.

Thezdrumsl, 41' Yof .crown gears 49, 49- errl tend radially; and .laterally where steering brake f effects are .applied .to `.graduate v.the retardation..

required to obtain the desirable steering effects.

Figs. 2 and 3 may be consulted at this point to clarify the action of the differential mechanism. The steering brakes A and B for the composite members 4l', 48, 49 and 4`I, 48', 49 are shown in part detail in Fig. 2, the plates El being splined to rotate with part 4l, and the plates 62 being attached to part to of the casing. The prime member parts at the right of Fig. 2 are similarly attached. The alphabet designations A and B in Fig. 1 are primarily to indicate the actuated steering devices; however, in Fig. 2 the brokenaway section shows portions thereof needed to understand in detail how the specific parts op-V erate.

Disregarding for the moment the power steering effect and assuming that the shafts 36 and 55 are driven together at unit speed from the engine by shaft 5, differential carrier 5, crown gears 49, 49' and coupling gears 43, 44, the fluid torque converter output member O may drive hollow shaft l, and assuming that the sprocket-shaft carriers 28, 35 are under equal torque and tractive load, the coupling pattern of the gearing requires that when either of bands 45 or 5I are energised to hold their drums 29' or I5, the reaction established by annulus gear 29 or carrier I5 compels the input power to be expressed as driving torque.

With band 45 locked for low gear drive, the carrier 28 and shaft 4U are driven in the same hand of rotation by sun gear I2' at a reduction ratio, while in the other output unit drum I'I and annulus I 8 are rotated equally and similarly since they are connected bv shaft 40.

The torque converter W may then be operated over its useful torque multiplying range, multiplied further by the reduction ratio of the output units. If the input sun gears I2 and I2 of the output units could be held against rotation, the annulus gears I8 and 33 would drive the carriers 35 and 28 at a fixed reduction. However, the power steering train is providing a fixed ratio drive from engine connected shaft 5, in the same hand of rotation, as will be obvious from a tracing of the rotations of the train elements.

Assuming that the differential unit D transmits power equally to the sun gears 24 and 38 of the two output shafts 2I and 31, and since the annulus gears I8 and 33 are connected by shaft 48, the drive operation in low gear proceeds by clamping brake band 45 on drum 29 of annulus gear 29 which causes carrier 28 and attached annulus gear 33 to rotate at a reduction ratio, which rotation would be transmitted to carrier 35 of output shaft 3l by whatever reaction or rotational component is applied to sun gear 38 from the mechanical train composed of the shaft 5, differential group 8, 48, 48, 43, shaft 36, gear 42 and gear 39 driving the sun gear 38.

The engine power applied to hollow shaft divides one component passing thru the torque converter W to shaft l, sun gears I2 and I2', nal drive annulus gears I8 and 33; the other component passing thru the differential group D- to shafts 33, 55, gears 4I, 42 and gears 25 and 39 coupled to the final drive sun gears 24 and 38.

The application of clutch 30-3I with release of band 45, couples annulus gear 29 with sun gear l2', compelling shafts 'I and 40 to rotate together, which places a similar couple across annulus IIS and sun gear I2 of the reverse gear group, so that the speed of uid torque converter output member O is applied to annulus gears I8 and 33 equally, the sun gears 24 and 38 receiving their components from the differential group D,

10 shaft 55, 36, gears 4I, 42 and 25, which latter drive the sun gears equally.

Alternate actuation and operation of clutch 30--3I. with brake band 45 provides two ranges of forward speed ratios, entirely suicient for all the needs of a large heavy vehicle.

To enable one to visualize clearly the relative rotational components of the various elements involved in this drive, the Figure l should be reexamined for the fact that the combined torque components for forward drive in the final output gearing are both of the same rotational hand as that of input; that is. the hands of rotation of shafts 5, l', 4D, of sun gears 24 and 38 and of cutput carriers 2G and 35 are the same.

The known prior art does not explain the utilisation of the dividing torque principle in differential power drives, nor does a general knowledge of this appear to be known in engineering practice or text books, hence it is believed proper to herein dwell at some length on it, that the invention may be properly and clearly understood.

Referring back to the conditions under which divided torque is obtained in low gear, it may be stated that the output unit sun gear 24, and ring gear I8 which participate in the recombining of the torque should have equal tooth loading under all drive conditions, and that the variable speed ratio torque path delivers a multiplication of approximately 3.5 to 1, in the present example, as shown, to the ring gear I3.

For ease of calculation, the tooth load times the pitch radius represents torque. The ratio of the gears I8 and 24 is 2.5 to l, therefore annulus gear I8 is always loaded 2.5 times more than sun gear 24. The speed ratio of the differential drive mechanical connection between sun gear 24 and the converter input shaft 5 is about 7 to l, therefore the incoming torque is that of the sun gear divided by 7, while that of the annulus gear is 3.5 times greater because of the torque multiplying planetary gear between the converter output member O` and the annulus IB.

The torque converter output and input torques are related by a factor R which varies with output speed, therefore the annulus gear torque depends on this factor, and upon converter output speed.

For clarity this statement may be set -up as an equation:

Coverter imput torque on shaft:

2.5 sun gear torque 3.5 converter ratio factor R The mechanical fraction of the input torque is:

Sun gear torque Since sun gear torque divided by 7 equals the mechanical torque, one can write:

Engine torque= 17.5 mechanical torque :mr-R) -i- 1 and therefore the expression Vfor the percentage of .input pover....earriedgbn the. .differential Mechanical torque 3.5 converter ratio. R..

Engine torque l7-.5+3'. 5 'converter ratio R- 1^ 4 It should be yunderstoodthat this demonstra; tion` is based on. .the mechanical dimensions Aand factorsjand onlyqhy(y wavof example,k and only serv l, I y Y f reasoning'yby which' tlrejfuseful results are achieved.

- Upon beingjgventhe ,torque n'iultiplication ra-A tios ofthe. ytorqueoriverter'for'the different outL put"j,SDee#S., on'ejnai' thereupon' by the above pressffdetermine[the percent' of the divided'I torque going thrujjthe tyvofpathsa A further, eXa'rnplewilll be helpful. Assuming the @engine running ;at'-f`ull throttle, with 'the' vfehicle standing f "stillv or j stalled, the.' 'mechanical drive' thru. the. planetary. seari mechanism' toms. theltorque Converter.; output.- .me r.,.O .'baekr. wards, .which with theproportional dirne' sionsfof thejparts shown in thedmv/ingsthetorqufniulf tiplieupri 'rene' iviiigrise te about-5; sci thetgtne powerl input ofthe mechaniealfdrive:

This characteristic vprovides a restraintupon enginel speed at 'stalling since only .percent of theelig'ie power V pas l resistance of whihzb'ui ginetorque value ata lo q l et' stauingfiess neet' is -gjeiieLettieri, but' iii/ ne i, vehicle's'tarts to move.'theoveralleiciency l isefsy',- because the aetue1-1esses'iritiie" Y are fin term values' rauch Aless tha'kn full t engine.'V powr...

This" characterisitioY appears Itherefore ,vasLprq-.l vicine e variabledietribiiibiief ui' terrines; d iii/ered by thetwe paths. witnrise ofthe co verter speed and zelcielCf'y rsultingliit'taking. a higher Aincrease in percentage 'arid Ithe'ni chanical drive taking alowerone.:.`

The" Ierallefciency obtained n a speedcharth. is a l'a'tte'rf'curve:than`v Wit'l'therilccinpara drives', and the corresponding engine V'speed Icha acteristic has a'rfincr'easngV upward'slope. The.; percentage of: torque.. toten. by. the v.meebor'teal` drive', inthe eample herewith given will, tween 15 and 50 percent, actually experienced.

When the clutchfgll, isrengagedjfonthe, hignjrforwarddriv the 3.5 to 1 ratio train between"contfe"' ""outputshaft 1 and the nal si to. showl theost'epsf` driveiiiis'a't 'trie'i'eftf'rid right ef Fig. 1 is ieeked 55 in ..d1.C..t' dlYe-...- BY;.1".h.S. @lining t 9T. llnglg ofwtherlative speed range, the percentage of divided torque is transferred. t9@ different scale in which the percentage'of 'the 'torque thru the mechanical train will vary between 22 and 5 60N percent,

This relationship of the divided and. recom-.1

forward speed ratios.

wTootsiere=.

la Fia 1,. fthe .hande-5l holding. drum l5; the.,

gear..- erobp.- .l 3.-..| 2..; @momiesV a reverse @..oQmRQeeM-.to onrlulus. gear. 18,-... If 2 l f. is .not rotating. the .euri eem' 2451111011111.: rota ,elforward.at2.5l times the .speed of they gear: lslwhichthruthefl.toll ratio of the gearingl traint@ f4l, Mhrotatdesthe torque converterinputl shaftat .17.5. tiniesthe. `speed ,of the annulus gear., I8. or '7 .times faster than the speed .of converter;V outputd shaft 1.

' Thereire.. wituineyenele. non in motion. the..

torque .oonvelftelr` output .Shaft .1 is rotating. ffor-. were? otono-seventh;oiinput Speed .enditheen--. orgy represented.. bmhie .rotation of Shafnlis fed back to the torque converter input shaft@ tbiioliSb-.the S.eme...eea111ewhieh; in forwardspeed dlrireeprovioeda.-reoombinine of toroueS-v.'

This novel .result ie not .textboohtheombuti represents .aotual -meohanioa1 .rfesultsroven by..

.-20 .beet....nstr.omelibatioa aswell as. bveuoeesoful. 011.-...

T. 1C; output torque=3.aT. C. input torque-- oriflitfollora-ibaia T. C. input torquefT. C. feed back torque=engine torque Since torque. converter l output, torque.. divided.T by? equals th'effeed ,back .torqueit follows that:`

' Xfeed back .torque=,.3...8 XT. C. input torqueI f @expressed enotbewey 1,.

C. feedl backwtorque Y 'r..c..inputterqiiere. feed backtorque=engine torque. we cansuhstituteh This. odd.eife :tA therefore resultsv in inducingan-l. increased input .torque, AI producing. a highertorque converter input. speed.' 'and-..inpu't.torque When reverseband 5 Lis. applied to carrier drum 65) whichfcaus'es. a. higher incrementalA value-of coni I5 for'planet' gears"lf3thegdividedatorque factors are reversed, and instead of the input power being divided. into two paths,1the arrangementpro.- duces the unusual effect `of. increasing the i drive.r

verter. output torque.. creating -the -anoinalyof# having .a net feverSelspeedlreduction .ratioff on1y...2.5lto lf as againstto 1` in.forward-lwratio,.y.et the 'reversefdriveoutput torque is higher input torque t0 a higher Value than that lbepng `70 ,thanthatin low...gear.ratio, becauselof thisfeeclv developed by the engine.

An analogy of this would be in .a self-energised brake.A rnelchanisui` Vin vlh'ic'shA the'brake another or reaction force 'nay be re-applied thru linkage to increasethe primaryenereisinc.force..."..

back. action.. This..novel..result..is not believed.v

heretoforeknown in devices -ofthis kind.l

Straightway. .forwardi driving .1 results in Athe e steeringdiferential mechanism .D rotating .as' a .unit smcetherghtand lefttread.forcereactions-- 13 are equal, and exactly divided by the differential action.

The steering brakes are not energised for straight driving. Clutch 54-56 being normally engaged, shafts 36 and 55 deliver equal torques to the nal drive output gear units, hence the output shaft speeds to the tread sprockets are exactly equal to each other, and equal in summation to the combination ratios provided by the fluid torque converter drive path and that thru the mechanical train.

Application of one of steering brakes A or B by energisation of the steering servo mechanism stops the rotation of the mechanical system driving one tread sprocket shaft, and doubles the speed to the other sprocket shaft.

When this occurs at a time when the fluid torque converter speed is low, the proportional and resulting steering effect is fast and the turnlng radius is short, whereas, if at high converter speeds, the resulting turning radius is expanded so that proportionally steadier steering is provided for high speed travel as against steering at low speeds by quick maneuvering with a short turning radius.

This effect of continuously variable steering radius increasing with drive speed is believed of exceptional novelty and utility in providing very accurate steering for large heavy vehicles under al1 drive surface and gradient conditions.

Common forms of slipping brake controls in this field of art are notorious for high energy dissipation requirements, and in the present invention, the matching of the drive characteristics of the units described herein produces a locked drum steering sequence which avoids need for excessive brake energy dissipation. It should be noted that regardless of vehicle speed, the speed effect derived thru the mechanical differential drive path is constant with constant engine speed, while that derived thru the hydraulic drive path is proportional to vehicie speed.

A further useful result herein is the fact that when the output shafts 2| and 37 are non-rotating, vehicle stopped, the application of one of the steering differential brakes A or B results in one tread being driven forwardly and the other re1 versely, which causes pivoting of the vehicle on its own center. In military practise, this feature is of exceptional value in enabling the tanks to reverse direction in a narrow space, and it adds also to operating facility in agricultural and dirt moving machinery.

Fig. 4 shows a hydraulic actuator for low band d5 which mechanism is also used for actuating reverse band rI'he band is pivoted at 'il to strut piece l supported in casing HJG by adjustable stud 'i9 and nut Eil. The movable end of the band is pivoted at 'i6 to strut 15 fitting a notch or recess in lever it pivoted to the casing at le. The lever 'i3 carries pivot 'i2 for link 1| of piston rod iiia of piston il! operating in cylinder 68 formed in the casing. Fluid pressure is admitted at Si to hold or push piston 'it against spring 69, and pressure on the opposite face of 1U is admitted and released thru passage B2.

The valve control system for the hydraulic servo action is shown in Figs. 9 to 20 inclusive, and described further herein.

The brake control of Figs. 5 and 6 pertains to the operation of the vehicle brakes 46 and 5G. When these brakes are applied, it is desirable that cooling lubricant be flowed at considerable velocity over the braking surfaces,

Band it is energised by pivoted strut 83,

notched arm 84, line 85, rocker arm 86, shaft 8l' and external lever S8 supported in casing iti?.

The lever Sii is rocked clockwise to energise brake t5. Main pump line pressure from the oil cooling system is connected to pipe S), and pipe Si is connected to an opening between the band i and the drum 28. The valve plug $2 is recessed to hold pressure in line t, and to withhold it from pipe 9i, and is held normally in the position shown when brake lit is not applied. Pron jection a of arm 86 registers as shown, until lever 88 causes arm 86 to swing for energising band de. Pressure in 9D thereupon moves valve 92 to the right, uncovering the upper end of pipe Si, so that cooled oil flows to the space between band and drum 28. When external lever 83 is moved to release brake d6, the projection 86a forces valve 92 to the left, covering the end of pipe 9|, stopping the flow from pipe t. This device provides brake cooling when it is needed, during the actuation period, and shuts it off when the cooling capacity is required in some other group of the system.

Fig. 7 shows the divided shafts 55 and 35 coupled by clutch C in a somewhat diierent space relationship of the parts of Fig. l. In Fig. 7 shaft 55 is splined to drum 53 with which plates 5d rotate and external drum 51 splined to shaft 36 carries plate 55 mating with plates 54.

The clutch C of Fig. 1 or 7 is for the purpose of maintaining an equivalent torque on both output sprocket shafts at all times except when a steering action is desired.

in Fig. 7 is shown the clutch assembly with plates 54 and 56 connected to drums 53 and 5i of shafts 55 and 36 respectively. The piston 63 in cylinder Sli is moved by pressure in passage t5 against a set of common disengaging springs not shown. The fluid pressure in passage 55 is controlled by valving which maintains pressure on piston S3 at all times except when one of the steering controls is moved to cause a steering effect. The method of steering control is described further in detail below, in connection with Fig. 16 and in a further system modification, in Fig. 17.

Fig. '7 shows a bevel gear differential system in place of the spur gear unit of Figs. l to 3, and also shows a modified steering clutch system discussed in detail below in connection with Figs. 9 and 10, pertaining to steering method. The drums il and i'i are splined to the axial sleeves of differential members i8 and 4B which are in turn toothed externally to mesh with gears 4 and d3.

Fig. 8 is a detailed view of the right hand portion of Fig. l, modified by the substitution of 'a disc brake construction for the band brakes of Fig. 1 for the vehicle.

In Fig. 8 modification, a friction disc brake i w3 is substituted for both the band brakes :it and 59 of Figs. 1 and 5, other novel features appearing. The output turbine O of the converter W is connected to shaft 'i thru splining, which shaft is shown integral with sun gear l2 and clutch drum Elia for plates .'i. Planet gears El meshing with l2 mesh externally with annulus gear E?, and are supported on pins 2l of carrier 28', xed to annulus gear 33 meshing with planets 34. Planets 3i, supported on pins 34 of carrier 22, mesh internally with sun gear 38 attached to gear 39. Carrier E23 is attached to sprocket wheel shaft 37 to drive same. Drum 29 of annulus gear 29 supports plates 3l mating with plates 3E and is formed to make a cylinder 2H for presser piston 2l5. The external rim of drum 29 is surrounded by brake band i5 as in Fig. 4, which is actuated ergangen lyk by A'the mechanism 'ries-cribed; inffconn'ecti'enffvtith Figs. 4 to 6.

fen Fig.4 8 the l drum 28 "of carrier'28 is splined externally to m'atching-'te'eth of frictionf discs 92 *mating Withidiscs |03splinedfto'itting'mattached -to 'the casingL |00, a 1 piece *|114 acting as the backing platefor-the stackof discs. Apressure plate |95 splinedto litting 5|04J-isattached vto ove`1"nangingVA member |305 having a radial 'an'ge for taking endwise thrust from-springs 5i-"06 seated'- in l a recess ofentting 21104. *Ring |01 `-is anchored in chann'e ES-between the overhang of fitting |104 1 and member I $15,` andx may-transmitthrust to the adjacent loose ring" 1F99 thru a ring-:offbearing ballsli-B.

The sec'ondringl09- lies inthe channel between tting I 04 and; member 05, to 'the vright of"ring I U11-rand 'isv ttedwith a sh'o'rt `arm 99 rocked A'externally by appropriatecontrols.

' The facingradial 4surfaces' of Yrin-gs 01 and 100 are machinedinto ovoidal sectionerecesses', not number-ed, in whichballs '|09'` are mountedfso that when relative rotation betweenthe rings-occurs; 4the balls 09 -ride into ythe 'shallower porf tions' v`of 'the ovo'idalsectionrecesses,= and exert an'axial thrust tendngjtopress ring |09 tothe "rightto shiftftting |05 Lto ithe'1 right against springs |06 thereby shifting plate |05- to` clamp the plates '|021 andii|03 together. This' form "of Vloading mechanism provides a high degree ofme- `'chanic'al *advantage 'for energising' 2the braking action forstp'pingfshaft 31 andsprocket wheel 31, in obtaining a pivotal steering actionforthe dual 'tread'vehclef or for' actual braking of the vvehicles drive motion.

The vclutch plates 3| `or Figs; 1A and 8are' released by springs; asshovS/n; and are 'clamped vby pistonL 21S-against' v'the opposing flangeJ` of "the 'drum 29 `of annulus' gear 29. Piston 2 |5"is"re cessed incylnder 2`| T vforrrled in""the".`drunVV '2 9 and better ishown'irrFig 8. 'The fluid pressure feed to'cylinder 2'|1"is"from`passage 218 (Fig. 8)

inthe casing'of oon-'verterW to a grooveand Taxial passage' 219 in the sleeve of shaft 1 leading'to a grooveregistering'witli passage 2`|4"'in the'sleeve i of drum 29', the' passage 2`|8"being 'shownin full 'line in Fig. 1l and'in"dashedzline'in'ligl 8. `The ^pressure control system" covering fthe'. pressure feed "to `'the low` and' high range'drive servo .cyl-

' connection with Fig. 14.

' Lubricating fluid frorn'the pumping system.. is fed by connecting passage 252, Fig. .1, to central passage 233 in shaft "40,'contin`uous with passage 258 in 'carrier -shaftJ31' of Fig;` 8. 'Radial passage 292, axial p'assag'e' 293 and diagonal passage 294 feed lubricant to the gear group "5| 2;21-1-29, and radial' passage'v 2'95 'delivers it. .to gear group 38-34-28. Spent oil flows back tothe sump as understood,Y further Vin "examination of Fig.' 14.

Referring back 5to Figs.y 2 'and 3, -passage'k`3l30 in shaft' 40 may" be continuous with passage 258 of Fig.' 8, andfeedlubricant'fthrunt'ersecting radial' passages 33 grooves'` 332, fand passages 'Figs'. 9 and 10 'show themechani'sm' foroperat-i ing the differential steering valves; |10 and |1| to`control the feed to"the"steeringv clutchl vacvtuatorsfoi Figs. 1, 2 and-'14.

In the preceding drive description :the Amechan-ical steering =effects"'obtain`d"by' graduated centers, is fittedv with a-roclcer'fplate |84 having "fingers E| 86v and T81 jat 'either' endlregistering-'with f* a:"chann`el-A in ithe slidable spring :seat vvcollarsr 18| and |82. n

-I `-The-'externalarrrr i|811 Vis held orr'shaft *|80 by r arserrated-section and'nut, and carries roller :|89 Afor coaction- 'witnextern'al f mechanical controls. "Seal"plugs '19| permit removal for'valve'repair pr adjustment.

Each bore |16 and |11, is equippediiwithlthree iportsy in order fromrl'eft to right; exhaust; `clutch VAfeed' andV main linedelivery. The Arniddleport "|-14for valve |16 connects-tothe 'cylinde58` of A"steeringbr'ake A for 4variable=braking of mem- 30 ber 41 V(if-"Fig,v 1,v whereas themddleport H5-for 'ing'brake B. -Each valvel is centrally drilled from fthe blind end of boss ,attheright to apoint'to the'left of that-boss, and the narrower neck portion'is cross-drilled at :|94 and|95 'to'4 connect thespaces betweentheboss'es tothe boreend spaces|6 and |91.

Infthe'vertical position of rocker Vplate|84both exhaust ports '|98 and |99 are connectedv tothe #40* actuatorpressure feedpassages 2|0 and 2| lead- `ing to cylinders 58 and 58 as in Fig.' 2 yandthe bosses f seal the pressure inlet'ports '20| and-'202.

:Rocking of the rocker plate |84`clockwisetends "to shift Aboss e of valve |1|'1eft toopen the 'ex- ,Lfhaust'port A|99 wider, while valve'I-10 is 'moved to the rightv to close'exhaust 'port |98 and open V pressure delivery port V20| to `the steering clutch Fig. 2 to slow down rotation of differential mem- "ber 41 of Fig.l 2,' for the desired steering effect.

*"The valve actionwill' be'described forvalve |10, inv which the linear spacing between-bosses e and f is so taken with respect to the 'spacing of "the'ports |98 and'20l that a very close control i over the pressure acting in the cylinder58 of the piston 59"-beirig'Y actuated, is obtainable. The

` cross-'drilling |94 connected to end space '|96 has the effectl of metering aproportional'fraction-of y the `linepressure `to the space |96' behind lvthe valve,- and since the interior pressurebetween the bosses ist equalized to prevent direct axial' force I 'onthe valve, theend-space pressure over the'end face ofthe Valve 'provides afor'ce proportional vto valve cross-'section `area'tending to shift'the B5" valve away from feedv actuation 'towardthelleft which itwill occupythe positionsho'wnin the 1`drawings herein. l

"Inotherwords the valve |10 and'y "|-'1| -tend 'to unload the steering differential 'clutches'A automatically.

However;v the operators control 'consisting' of arm 81E- of shaft worked by external mechanisrn coacting with'roller A"|39 pinned to the arm |88, applies a force acting'thru-calibrated'springs f- '203, 2'04, the force pattern providing a range of equilibrium points in the motion capable of being felt as a small variable reaction force on the operators control arm |88, so that in steering the vehicle, the operator is able to maintain a very smooth, tactile adjustment on the steering valve action. It is believed novel to provide pressure reaction feel in control devices for manual valves which regulate the differential steering of drive mechanisms such as described herein.

The resulting self-compensation between spring-force, valve position and net pressure in end space |96 provides automatic adjustment of the net steering brake pressure.

It is not deemed necessary to describe the opposite steering action by which valve |1| regulates the actuation of diierential actuator B for member 41' of Fig. 2. The overall control diagram of Fig. 14 will be better understood by reference to Figs. 9 and 10.

Auxiliary cooling for the steering brakes A and B is provided for, one method being shown in which the pressure passages |12 and |13 of Fig. 14 are connected to jet passages 322 and 32| respectively; delivering to a pair of jets 3|8, 32| one for each steering brake. This method provides additional cooling ow during all intervals when the steering brakes A or B are under fluid pressure actuation. A second method in which the cooling flow is taken from a lower pressure portion of the supply system is shown in Fig. 17.

Fig. '7 shows a modication form of steering differential in which a bevel gear replaces the spur gear differential of Fig. 2; in which the straight drive clutch 54, 56 is shown nested inside the compensator gears 43 and 44 between shafts 36 and 55; and in which the diierential steering brake members 41 and 41 are braked by electrical means.

In my said co-pending application for Letters Patent Serial No. 588.475 led April 16, 1945, is shown a schematic electrical steering control in which appear a simple divided resistance circuit connecting each resistance half with a corresponding electrical braking coil which receives an increased current with steering angle, from a source of electrical power, as controlled by a selective resistance arm, manually operated. In that disclosure, the energising current is deliv.- ered thru a governor-operated switch which cuts off the steering current at below a given governor speed, but the governor switch may be by-passed by a manual switch if it be desired to utilize the electrical. steering action under speed conditions wherein the governor would have interrupted the power steering circuit. The manually-operated 'f steering contactor arm of the Serial No. 588,475 disclosure may be used as a cut-oir switch by being placed in the non-steering middle position temporarily, and further, the governor of that showing may be replaced by a simple manual switch. The field magnets are designated by numerals 51 and 61' in Fig. 7.

Present reference to the copending application showing is to provide adequate means for steering control by the modification. structure of Fig. 7.

In that iigure, the drums 41 and 41' rotating with the members 48 and 48' serve the same purpose as drums 41 and 41 of Fig. 2. The eld coils 66 and 66' respectively supply actuation energy for A and B. For steering braking of differential member 48 coil 66 is energised, generating a magnetic iiux of proportional value in the plural pole assembly resulting in a braking of 18 drum 41, since the assembly inside which coil 66 is mounted, is bolted to an extension ||l0d of the casing, as shown. This braking method is old and well known in the art as eddy-current braking.

This phenomenon is obtained in squirrel-cage induction or in synchronous motors, designed with salient poles and D. C. excitation, the squirrel-cage member being usually a solid iron or steel drum or cylinder as a rotor in which the eddy currents are induced. The D. C. excitation is used to obtain smooth adjustment of the torque capacity, which decreases at lower speeds.

In the Fig. 7 showing the drums 41 and 41 are the iron or steel rotors, in which the eddy currents are induced, proportional to the current selectively applied to cores 66 and 66. Since the desired steering effect is more gradual than a direct stopping effect for other than emergency fast pivoting steering, the electrical method is adapted to provide a iine control of net steering over a considerable and wide turning range. The structural nesting of the differential gearing, the split-torque delivery gearing 43, 44 and the steering brakes A and B of Fig. 7 demonstrates an advantageous feature of the modification showing. Jet cooling of drums 41 and 41 is described further in detail below.

It is not thought essential to reproduce herein the above-noted Fig. 3 of my said priorly filed application U. S. S. N. 588,475, for a comprehension. of the full utility of Fig. 7 of the present disclosure.

Fig. 11 should be oriented with the diagram of Fig. 14.

In Fig. 11, valve Ill) is shown located in a sectioned portion of valve body 200. The external end of the valve I0 is moved by arm of shaft ||2, thru pin I3 intersecting two bosses of the valve, so as to convert rotation of shaft H2 to rectilinear movement of the valve Ill). The Fig. 12 view clarifies this motion coordination. Arm H2 of shaft |I2, with roller |4| coacts with the operators control.

For ease in identifying the parts, the bosses of the valve llil are lettered from top to bottom as a, b, c and d. As shown in Fig. 11, the bore |4 for valve |||l in body 260, is intersected by port spaces numbered in the same sequence ||5, ||6, ||1, H8, ||9, |20, |2| and |22.

The upper two port spaces I5 and I6 are connected to the pressure feed line 208 and passage 8 of Fig. 14 to deliver fluid pressure to the servo cylinder for the piston operating reverse band 5| of Fig. 1, with an actuator structure equivalent to that of Fig. 4, operated by a counterpart of piston 16.

The third port ||1 from the top of Fig. 1l is connected to pressure feed line 250 of Fig. 14 receiving line pressure thru the main line regulator valve space |55 and line 25) connected to the pressure delivery sides of the pumps 300, 30| of Fig. 14.

The fourth port 8 is cross-connected by passage |23 in the body 200 with the seventh port |22 for reasons to be explained further below.

The nfth port I9 is the feed port for the actuation of band 45 of Figs. 1 and 4 and connects to the passage 3| of Fig. 4 for that purpose, thru feed line 26|. The line 26| is connected laterally to by-pass valve 26|] of Fig. 13.

The sixth port |26, is connected to exhaust or to the spent-pressure passages leading to the sump 3|4.

The seventh port |2|, is connected to passage 'fa-,annota E259 leadingtovthe:passages12|18, 2I.19:=an'd 2|4tto t'he cylinder 12 I1 for v'actuating the .high-range :clutchpiston: 2 I 5 fof '.Figr V8 and is; connected :by -fpassage I 66 to :the chamber I 65. at the .bottom V*of the regulator valve bore |53 of Fig. 15, to acton fthe; lower .faceof `the '.boss z', under :certain control circumstances.

.'Ihe space 1 I 24 Iat the :base tof .'the 'distributor .Ishifter valvei ILO is openitozexhaust griassagel'. When the-.boss a of valve I I `is below the'ports lztand ||6, .theseaports mayldrain upwardly :past-:the .narrow neck :of 'the 'valve stem. into .spacer-|21.

'The:ratio-deterrnining4 positions for valve I I 0 arermarkedgon the drawing of Fig. 14, in order `fronithe rtop' .R, .H, .L,:and .N, representing :reverse high frange, low;range :and neutral, zrespectively.

As.. shownin .-Figs. 11 and.1.4 ftheffeedV port I' I I is open above pboss b Vto deliver .reverse reaction :pressure-at port I I6to'clarnpfthe band 5Iof Fig. .l10n drum I5, while the ports .I ISand |20 are sealed from exhaust.

TIn-this reversepostionfR thezlowe'range feed portl |91is open tothe port f.| |18.cross-.connected lwith :port t |22 the high-range .port Y1| 2 I is .open to exhaust port:|20. Sincerboss d is'above the port |22 therrossfconnection passage |23 :and :port I IIB. are open to exhaust at.|26.

lrIn zthe'next "\.1I;positionfA the vboss bis. stationed :between lports I.|8.and :|I9,.solthat`:line pressure in .port f|`|11 may :passto .port 'I I'8,".thru passage |23 to ports |22 and I2I for delivery to theihigh- :range clutchiieed passages'i259; and Iii,- and-boss d seals port |22 from exhaust.

fReverse Vvport F5 is 1 at i this time. opened .to :eX- vhaust. at 1 If2I and'. low-rangelport i I I9 is `exposedto rexhaust port I'20`betweenl bosses'b and c.

'The nextstation,downwardfiszat point .L.of lthe sequence marked iin Fig, v14:, in rwhich the upper -edge of boss -a fis at the flower edge :of reversefeedport '.I I6; the lower edge of boss'b is at 'the upperedge lOfiline-connected port fIrII; boss b blocks release fromlowrange-port'l I9 to exhaust port |20, andbosses c-and dzprevent.

Aexhaust from the .cross-connected ports ||8 and |22. :Feed-is therefore *fromvthe pump line port v|I1 to low-range port I|9-for actuation `of low gearband 45-ofFigs. 1 and'4.

The last end-station downward is fN,.and.reg 'isters the lower `edge 0f Vboss a with .the lupper edge of port ||-8; placesbossb between exhaust -port |20 and yhigh range portr|2| places boss c between cross-connected port |.22-andspace |24, rand leaves boss d outof ythe wayfin space .|24. 'In this -circurnstancethe main feed port 1I I1 is sealed by boss a and all of the feed-ports .I I5, I6, 6 and I 2 I'are open-'to exhaust.

Thevalve |||J lmay be freely moved amongthe fourpositions, and in each position for delivering servo actuation pressure to the 'variouscylinders prevents any wrong motion delivery by :the peculiar port and boss arrangement, believed to possess points-ofnovelty in thisart.

V'It fis not deemed -necessary to show fthe external mechanical motion for operating :valve Iltlbeyond arm H2 and roller |4I since poppeting actions for `valve-stationing and port 'reg- :istry are old inthe art. The roller |4I 'for example may be traversed over a poppeted sector, .the Vinterpoppet spaces being located angularly ,to correspond to equivalent angles for arm as determining the stop stations'marked in Fig. v1.4:.

Persons skilled in the vart may v`adopt this --teaching as' desired '.ormeeded, without :exercise rofl invention, and obtainutheuseful resultsfzofa-the :present device.

,Itisproper to review-Fig. Min connection with vthe .by-epass valve .260 shown in Figs. 13 lfand 1,114 locatedin the pressure feed line..2'6|,betweenthe v'distributor valve ||0 and the .cylindennofzthe low zrange .drive Aactuator'piston Iior brakezt (Fig. 4).

vEngine vacuum iderived in .passage262ifrom the engine intakefmanifold (not shown) :is'admitted to space 263 'so as .to "vary'the'suction pull on diaphragmf264 acting against spring .'265. lThe valve plug a2 60 seats at :2 664 against' the pres- -suretofrv line 26 I tending' tolift'the: plug :260 'from the :seat ;266 and .by-pass riluid into-space #26T connectedto the spent' pressure line 268, 'which line 'pressure "meets 'fthe resistance of vcalibrated spring 265.

The diaphragmA 261|.is .equippedwithabutment pin VZ269 :which :may :strike :adjustable .stop pin H'IU; at agiven valvezopeningtspa'cing.

"When 4pressure -is :admitted .by =valve 21260 L'to line li268, 'the existence of a 'high :degree .of ivanuum ltends 'to idravv fthe diaphragm "to 'itheright inkl-lig. .13 rpermittingtheiplug 260 to'movefun- .restricted i'to 'the rightzfor ffull port iopeningiat .1.266. If the `degree'of engine vacuum is lcw'fas Awhen the iengine .'may be under-heavy load, 'the .force Vof fspring'265 'tends 'to .limitthe opening 'between .plug :260 .and 266, iso :that .the vamount 'of uid relieved is lessfandthe 'rise' of low Irange 'actuating' pressure may 'occur :more `rapidly.

vThe :force of fspring'265lis .'c'hosen .to holdthe valve closed :normally against rthe pressure fof passage 26|.

This action is Y conditioned by tthe accelerator lever motion and setting. If the driverfs `lever setting,fforexample-lever1315 of Fig. 20iisdiminished toward idling, vthe manifold vacuum force vmay increase, causingthe fplug2|5|i` to 'bleed off line pressure .to :a :predetermined :.low value, -Whereas ifzthe lever is fadvancedtoward avhigher 1engine powersetting, l.the 'vacuum yforce drops in value, and 'the spring .265'loads'plugfZIiIlv on the seat 266,-to'closefoizthefby-pass'line 268'1therefby causing the 'line y.pressure for .establishing :the low :range vactuating ipressure to remain high, thus providinghig'hreaction torque capacity.

The-initial ylow pressure Aphase results intrest lowerange actuation aunder .dcwnshift from rela- 1tively low reaction`torque'capacity for brake 45, whereas Ythe .high l.pressure phase produces .a .higher'torqueY capacityibuild-.up more quickly.

The degree of low-range actuationis utherefore` commensurate with enginethrottle position, and ,the .invention .herein .in this particulai-.is .believed to representnovelty over-.prior art disclosures .in which variations in the degree 0'! vacuum .are utilized in Adevices which modify automaticratio changing controls, and in .which the force available for clutching is so varied.

The -`mechanism of Fig. 13 may be built into'a common control housing such as valve body 200, .as numbered herein, or placed `elsewhere for the convenience ofthe operator, as'laid out by the designer.

`Figure 14 is given to instruct the reader on the coordination of the many lfunctions and operations involved in the-control, actuation, working fluid supply, lubrication `and cooling ofthe drive mechanism.

The pressure supply sources are located at the lower right of the ligure, the main line 4regulation and vservo pressurefdelivery controls at the 

